Narrative:

First officer had just leveled off at FL240 when the flight attendants called us again for the third time since 10000 ft saying they were still freezing. I had already made 3 adjustments in automatic mode to warm up the cabin. I made the next adjustment to the right pack in manual mode so I could control and see if warmer air was being delivered to the cabin since it was not happening in automatic mode. With a small increase in heat to the right pack, I got a right pack trip and flow light 'on.' the left pack was still in automatic, but couldn't maintain cabin pressure. The cabin started to raise slowly. I had the first officer stop climb, which he did through ATC at FL270. With the cabin still climbing, I asked ATC for a clearance to 10000 ft because of pressurization problem. ATC gave me a clearance down to FL180, but said it would be a few more mins before he could give me lower. I didn't want to level off at FL180 to see if I did get lower before I got to FL180, so in the interest of safety under the circumstances, I declared an emergency and asked for an emergency descent down to 10000 ft, which he granted. We reached 10000 ft before the cabin oxygen mask dropped. I informed the flight attendants we had pressurization problem and we were descending down to a lower altitude. Asked ATC for a clearance back to ewr as a precautionary measure and a safe course of action to take. We did not have anyone hurt or injured, landing in ewr was normal. On the return to ewr, I called operations and maintenance about our situation as well, and the flight attendants and passenger were informed.

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Original NASA ASRS Text

Title: AN MD80 CREW, AFTER DEPARTING EWR, EXPERIENCED A LOSS OF CABIN PRESSURE, SPAWNING AN EMER DSCNT TO 10000 FT AND A RETURN TO EWR.

Narrative: FO HAD JUST LEVELED OFF AT FL240 WHEN THE FLT ATTENDANTS CALLED US AGAIN FOR THE THIRD TIME SINCE 10000 FT SAYING THEY WERE STILL FREEZING. I HAD ALREADY MADE 3 ADJUSTMENTS IN AUTO MODE TO WARM UP THE CABIN. I MADE THE NEXT ADJUSTMENT TO THE R PACK IN MANUAL MODE SO I COULD CTL AND SEE IF WARMER AIR WAS BEING DELIVERED TO THE CABIN SINCE IT WAS NOT HAPPENING IN AUTO MODE. WITH A SMALL INCREASE IN HEAT TO THE R PACK, I GOT A R PACK TRIP AND FLOW LIGHT 'ON.' THE L PACK WAS STILL IN AUTO, BUT COULDN'T MAINTAIN CABIN PRESSURE. THE CABIN STARTED TO RAISE SLOWLY. I HAD THE FO STOP CLB, WHICH HE DID THROUGH ATC AT FL270. WITH THE CABIN STILL CLBING, I ASKED ATC FOR A CLRNC TO 10000 FT BECAUSE OF PRESSURIZATION PROB. ATC GAVE ME A CLRNC DOWN TO FL180, BUT SAID IT WOULD BE A FEW MORE MINS BEFORE HE COULD GIVE ME LOWER. I DIDN'T WANT TO LEVEL OFF AT FL180 TO SEE IF I DID GET LOWER BEFORE I GOT TO FL180, SO IN THE INTEREST OF SAFETY UNDER THE CIRCUMSTANCES, I DECLARED AN EMER AND ASKED FOR AN EMER DSCNT DOWN TO 10000 FT, WHICH HE GRANTED. WE REACHED 10000 FT BEFORE THE CABIN OXYGEN MASK DROPPED. I INFORMED THE FLT ATTENDANTS WE HAD PRESSURIZATION PROB AND WE WERE DSNDING DOWN TO A LOWER ALT. ASKED ATC FOR A CLRNC BACK TO EWR AS A PRECAUTIONARY MEASURE AND A SAFE COURSE OF ACTION TO TAKE. WE DID NOT HAVE ANYONE HURT OR INJURED, LNDG IN EWR WAS NORMAL. ON THE RETURN TO EWR, I CALLED OPS AND MAINT ABOUT OUR SIT AS WELL, AND THE FLT ATTENDANTS AND PAX WERE INFORMED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.